In the context of energy saving and optimization, it becomes of interest to utility providers or any other organizations, to be able to control energy use. The need for limiting consumption can be often predicted in advance since peak usage is usually predictable, for instance by comparing past usages and/or by anticipating on the temperatures of the next days. Some usages may be seen as less critical than others and could be temporarily set in a lower consumption mode, typically in case of energy shortage risk. For instance, enforcing heating system to not heat over a temperature of 18° or 20°, or enforcing washing machine to delay its start could be possible solutions.
For customers that consume large amounts of power, the process for limiting consumption can be made manually, by contacting the clients and by recommending to lower the power loads. However, such a practice is laborious and slow. Moreover, voluntary reduction of power loads is often insufficient and compulsory reductions become necessary when power utility companies are temporarily not able to fully supply the electrical power demands for all users during peak usages.
Today, owing to smart grids, automatic measure for limiting power consumption can be achieved, for instance by sending “On” or “Off” messages (respectively to an active and to an inactive state) to an electric appliance connected to such a smart grid. However, some people may want to block such messages to circumvent the feature so that they are not bothered with service reduction. A possible solution against such actions could be to ask the devices to acknowledge the requests for disabling, but this leads to scalability issues with complicated handling on the server side and multiplication of upstream messages that may overload the network. Furthermore, acknowledgement of compulsory request could be also tampered by sending a fraudulent acknowledgement message.
The document US 2009062970 suggests such a system for managing consumption of power supplied by an electric utility to power devices of clients. The system includes a server storing information relating to power consumed by these devices. When a power reduction is requested by the utility, the server selects, on the basis of this information, at least one client device to which to issue a power reduction message by means of a “Turn Off” message. Once the power reduction is no more necessary, the power consuming devices have to receive a “Turn On” message in order to be switched back on. Acknowledgement message is sent to the server in order to confirm that the transaction has ended.
The document US 2005065742 discloses another system for remote power management using a wireless communication link. The system comprises three main components, i.e. the end device (e.g. an air-conditioning device), an energy management host processor acting as a host server and an access point ensuring the wireless communications between the end device and the host server. This access point could be a smart power meter. For example, the latter may transmit, to the end device, a command to deactivate a load. After having recognized the message, the device processes the instruction in order to disabled the appliance. Besides, the energy management of this system includes utility meter reading. The host server is typically a large-scale server capable of processing simultaneous communication with numerous remote end devices. It can record the status as to whether a utility meter is active or inactive. For example, a utility meter may be shut off to disconnect power when a residence is vacated. The host server is also able to request the access point to poll the end device in view to get energy status indications. Alternatively, the access point can communicate with the host server by using the power line infrastructure as physical medium for transferring data. This document does not teach any specific manner for preventing the system against people wanting to block command messages nor against people seeking to skirt the suggested communication system.
The document US2011/196547 discloses an energy management system providing power saving function for controlling power of home appliances within the user area. To this end, this system is provided with an information receiving unit for receiving electric rates (e.g. from power company) through a smart grid network. With such information, a power control unit can automatically control several appliances, separately, by means of a communication unit which connects the home appliances to the energy management system within the user area. At any time, the user can switch any appliance from a power saving mode into a manual mode by means of a user command. Accordingly, the suggested system is not a restrictive system for the user since the latter can switch at any time one or several appliances in the power mode of his choice.